Chapter 1 (METHODS) - Histoworld Flashcards
When using a compound microscope, objective lenses can be found to have a magnification of all of the following, EXCEPT?
1000x
What is “compound microscope”?
Microscope with two lenses
- A compound microscope has two lenses: an eyepiece lens and objective lens. The eyepiece lens usually has a magnification of 10X. There are objective lenses on the revolving nosepiece with varying magnifications. Most compound microscopes have objective lenses with magnification of 4X, 10X, and 40X. Some compound microscopes also have an oil immersion lens with a magnification of 100X.
What is the total magnification achieved with a compound microscope?
d. Magnification of ocular lens multiplied by the magnification of the objective lens
* To calculate the total magnification achieved with a compound microscope, the magnification of the ocular lens is multiplied by the magnification of the objective lens. For example, if viewing a sample with the 40x objective, the total magnification would be calculated as follows: a 10X ocular lens used with a 40X objective lens, the total magnification is 400X (10 x 40).
What is the maximum resolving power seen with a compound microscope?
- 2 micrometers
* Resolving power is the ability to see two things as discrete images. With normal vision, there is a resolving power of about of 100 micrometers. A compound microscope has a resolving power of approximately .2 micrometers. In other words, two marks .2 micrometers apart can be seen as two distinct entities. Any closer than this, they are perceived as one object.
What is the turret?
Nosepiece
On a microscope, what structure connects the eyepiece to the objective lens?
Tube
- The base is the bottom of the microscope. The revolving nosepiece is also called a turret. The objective lens is attached to the nosepiece (or turret). The slide rests on the stage. The tube is the structure which connects the eyepiece to the objective lenses (it is shaped like a tube; thus, its name). The diaphragm controls the diameter of the cone of light.
In a good compound microscope, the focus knob does not have to be readjusted when changing the magnification. What is this phenomenon called?
Parfocal
- Parafocal is the term used for a microscope if the focus knob does not have to be readjusted when changing the magnifications. This phenomenon is seen with good compound microscopes. In other words, when the specimen is in focus at 4X and the objective is switched to 10X, the specimen remains in focus.
What is another name for the light microscope?
Compound microscope
Which microscope does not rely on visible light?
Transmission electron microscope
Which microscope makes things appear three dimensional?
Dissection microscope
- A simple microscope has only one lens. A compound microscope utilizes two lenses: an ocular lens and an objective lens. The compound microscope is also referred to as a “light microscope” or “bright field microscope”. A phase contrast microscope is useful for examining living cells, because the specimen does not need to be stained. A dissection microscope uses low power magnification. Things appear three dimensional with a dissection microscope. A transmission electron microscope does not use light, but rather a beam of electrons.
When using a compound microscope, what is the magnification of the oil immersion lens?
100x
What is the usual magnification of the ocular lens on a compound microscope?
10x
- The usual magnification of an ocular lens on a compound microscope is 10X. Some microscopes have a 15X eyepiece lens. The ocular lens is the lens at the top of the tube, the one that you first look through when using a microscope. It is also called the eyepiece lens.
When using oil immersion to view a tissue, what is the refractive index of the oil?
Same as glass
- With light microscopy, there normally is a space of air between the slide and the lens. Oil immersion replaces that space of air with oil. The refractive index of the oil is the same as glass.
What is the role of the condenser lens?
Focus the light on the specimen
- The role of the condenser lens is to focus light on the specimen. It is used with higher magnifications.
On a microscope, what structure varies the diameter of the cone of light?
Diaphragm